Learn what these terms mean and continue playing *the Electric Shocktopus!*

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Learn what these terms mean and continue playing *the Electric Shocktopus!*

This lesson reviews the concept of **electric charges** and teaches the students about **magnetic fields** and **Lorentz force**.

**Theory**: This lesson introduces your students to the concepts of magnetic fields and Lorentz force.**Play**: Students get to continue playing*the Electric Shocktopus*.**Share & Discuss**: These tasks focus on understanding both magnetic fields and Lorentz force.

- There are two types of electric charges. What are they?

Positive and negative charges.

- How do electric charges react to one another?

Similar charges repel one another. Different charges (+/-) attract one another.

- A charge is one type of electricity. What is the other type and what is the difference?

A charge is a stationary kind of electricity. The other is a current, which is a mobile, moving kind of electricity.

**You can give the students a few minutes to think about these answers, but they won’t likely need a long time because these questions aren’t all that challenging.**

Image Source: *Electric Charge*, Wikimedia Commons.

- A
**region**around a magnetic material or a**moving electric charge**within which the force of magnetism acts - A magnetic field is generated when electric charge carriers such as electrons move through space or within an electrical conductor (source)
- Properties of a magnetic field are rendered in
**electromagnetism**, which is the basis of technological advancements such as bullet trains, elevators, escalators and cathode-ray tube televisions (source)

Use your own sources and the ones below to teach the concept of magnetic fields to the students.

**READ:**

- WhatIs.com: Magnetic Field
- HyperPhysics.edu: Magnetic Field
- UniverseToday.com: Magnetic Field
- KhanAcademy.com: Magnetic Field (includes excellent illustrations)
- Physics4Kids.com: Magnetic Field

**WATCH:**

- One Minute Physics: Magnets (6 min)

- Lorentz force, the force exerted on a charged particle
*q*moving with velocity**v**through an electric**E**and magnetic field**B**. The entire electromagnetic force**F**on the charged particle is called**the Lorentz force**(after the Dutch physicist Hendrik A. Lorentz) and is given by

**F**=*q***E**+ _q**v**×**B**.

(source)

This concept probably seems much more intimidating to students than it actually is. It can be a good idea to illustrate this concept with a few exercises that you can solve together.

**Reminder:** As taught in the previous lesson, an **electric field** is “a region around a charged particle or object within which a force would be exerted on other charged particles or objects.”

**READ:**

- Encyclopaedia Britannica: Lorentz Force
- Conspiracy of Light: Explaining the Lorentz Force
- IsaacPhysics: Lorentz Force (includes excellent exercises)

**WATCH:**

Image Source: *Hendrik A. Lorentz*, Wikimedia Commons

Now is time to play the game! **Optional challenge**: Earn 3 stars in as many levels as you can.

CONTROLS
Movement - arrow keys / WASD

Activate charge - shift / Z

Restart level - R

Menu - ESC

**Pay attention to -**

magnetic fields

Lorentz force

Leave this slide open while playing, and move on to the next phase when there is about 10 minutes remaining.

The “Pay attention to” segment includes topics that will be discussed in the tasks at the end of the lesson.

If some students are having trouble playing the game, be sure to help them. You should, however, leave them with a chance to try in earnest before giving them any solutions.

To begin, click on **Let's Rock**.

Click a level to play it. To see more levels, click on the arrows.

- How far along did you get?
- Did you get 3 stars in a level? How many times did you manage to get 3 stars?
- Did you need to skip a level? If so, what made it difficult?

These questions are meant to get the students to open up and start a discussion. The answers do not matter as much as the fact that they are talking: the next slide provides opportunities for evaluation and should be more strictly observed.

What is a **magnetic field?** What creates a magnetic field?

**What is a magnetic field:** A region around a magnetic material or a moving electric charge within which the force of magnetism acts.

**What creates a magnetic field:** A magnetic field is generated when electric charge carriers such as electrons move through space or within an electrical conductor.

This is the equation for Lorentz force:\

**F** = *q***E** + *q***v** × **B**

What does each letter stand for? What is the Lorentz force?

**Key to the equation**: *q* = particle, **F** = force (the titular Lorentz force), **E** = electric field, **B** = magnetic field, **v** = velocity of the particle

**What is the Lorentz force:** The force exerted on a charged particle *q* moving with velocity **v** through an electric **E** and magnetic field **B**. The entire electromagnetic force **F** on the charged particle is called the Lorentz force.

It’s a good idea to let the students think about these answers for a moment before asking them - if you so wish, they can even check the game for the answers if necessary! Below are the expected answers for these questions. If you have time, you can demonstrate the answers in the game itself.

**You can also let the students know what the topic of the next lesson is: conductors and insulators!**